Has anyone put a small shot of nitrous on there jeep? If i had a small sneaky pete i may would hook it up just to have a little extra pup whenever i felt like i need it but i wouldn't put more then like a 20 or 25 shot.

Ya i'm sure up to a 75hp shot would be fine.For a 20-25hp shot you shouldn't need new fuel injectors or a computer reprogram.For 20-25 a dry shoot is okay but when you get into the bigger shots a wet kit is better. Also be sure not to hit the rev limiter on the engien when the nitro is on.If this happens the nitrous can build up in the intake a then blow up and on some cars it can blow the intake off the engien.

I had a different experience. It will not "bolt straight up". One little dohicky (official term) on the throttle bodies is different. There is a little tab on the dohicky that points downward and prevents putting a 4.0 TB on a 2.5 and vice versa. You must pull this dohicky off the 2.5 TB and put it on the 4.0 TB and then it bolts right up. As someone else said, make sure you get a new gasket before doing the swap though.

I did notice an improvement on the top end also. Good $50 mod.

I run into the same problem when I did mine 2 days ago, rather than remove the tamperproof screws I opted for a more...... um........ aggressive approach and just popped the tab off with a pair of pliers, and VIOLA'. I did notice a mild improvement in throttle response.

My TB didnt come with IAC, TPS or MAP so I had to swap mine. The IAC housing is different. The hole inside is larger on the 4.0. I originally installed it by hitting the little tab with the grinder but I had a crazy idle. I also didnt have security Torx bits, but I borrowed a set to swap the IAC housing. Paid $28 shipped to my door. Im going to pull it off and port match it to the gasket.

Only that validated dyno tests... which should never be confused with the always overly optimistic butt-dyno... show no gain by doing that. In fact, Jp Magazine tried installing a 4.0L throttle body onto a 2.5L engine a year or two ago and they actually noticed a slight drop in performance. And I don't care what someone's butt-dyno is telling them who says it helped their performance. The Placebo Effect is a strong one that is hard to resist, that is for sure.

I have a 94yj with 4 pissed of gerbals in it. So if im getting it right, you all are saying that a 4.0 TB bolts right onto the 2.5 and will give me gerbals more food? and with a spacer say like a vortex or something same will help and someone who is not a master mechanic can do? Is there a photo log of the conversion anywhere?

A spacer won't do jack for the type of air-only throttle body the TJ uses. Spacers can do wonders when under a carburetor or the old no-longer used TBI (throttle body injection) systems that are "wet" because they have fuel passing through them but the TJ has only air passing through its throttle body.

And regardless of what 4bangerjp.com/ says about what they found with their dyno by using a 4.0L throttle body on the 2.5L engine, it's still pretty well agreed on that a 4.0 TB does nothing for the 2.5L engine. And one thing to know about a dyno... they are not (!) a precise device. You can run five different dyno tests on the same configuration and even if you try to get the results the same, you'll get five different results. Its error rate is greater than the dyno hp gains claimed by some.

The 2.5L isn't starved for more air, it is starved for more displacement.

Well my friend maybe the people don’t buy them. This vehicle was a gift to my girlfriend from her father. I understand there is no cure for displacement, how ever I thought this was an area you could ask questions and not expect to get ridiculed or belittled. I guess I was wrong. That is too bad.

Well my friend maybe the people donít buy them. This vehicle was a gift to my girlfriend from her father. I understand there is no cure for displacement, how ever I thought this was an area you could ask questions and not expect to get ridiculed or belittled. I guess I was wrong. That is too bad.

Nobody meant any harm. You were given good points on both sides of the fence. We all like to ruffle feathers every now and then, lol.

Why would anybody buy a Jeep with the toy 4 banger anyway? Don't they drive it first and see it has no power?

Same idea as people moving by an airport, then complaining about the planes.

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Well, I paid $1200 for my 1998 Jeep with the "toy 4 banger" and 70,000 miles on it. That's MY "excuse", anyway!

I did the 4.0 TB swap, as well as enlarging the manifold and better exhaust. My butt-dyno says it has some improvement, but never actually dyno'd it. "Experts" say it's great/waste of money, depending on who you ask. I'm glad I did it, but that's my .02.

i got a 4 banger because i drive mainly just around town and dont commute for work. there for the less-crappy mpg of the 4 banger is favorable and the lack of power is rarely a problem. i do drive over the hill once a week or so to visit freinds and could use a slight bit more torque so the 4.0 TB with a spacer and K&N filter is more helpful than the extra two cylinders.

Sorry to inform you that a throttle body does nothing when placed under the type of throttle body a TJ has. Spacers like that can help performance with the older TBI (Throttle Body Injection) style of throttle body with a fuel injector screwed into it, as well as with carburetors, but it won't help in the least when installed under a TJ's throttle body that has nothing but air passing through it.

Sorry to inform you that a throttle body does nothing when placed under the type of throttle body a TJ has. Spacers like that can help performance with the older TBI (Throttle Body Injection) style of throttle body with a fuel injector screwed into it, as well as with carburetors, but it won't help in the least when installed under a TJ's throttle body that has nothing but air passing through it.

x2; been there done that on my 2.5l. I'd chalk most of the improvements up to the placebo effect.

The 4.0L TB will add some on the top end if anything. The 2.5 is flowing enough air through to really gain anything. The difference you feel in the low end is strickly due to the fact that the bore is large hence allowing more air in than a small TB at the same throttle plate position....it's more 'snappy' or responsive off idle. The PCM compensates for the extra air, so it is not an actual power gain.

Where the 4.0L TB really starts to help is when you have done some mods. My 95 YJ 2.5 had the 4.0L TB, 2.5 cat and cat back, MAP adjuster, Jacobs ignition, and a few other tweaks. It was quicker, but it was mostly at high RPM. It was quicker light to light than a co-workers bone stock renix YJ, and that was with 31's on mine.